$-\dfrac{2}{6} + \dfrac{1}{12} = {?}$
Solution: $ = - {\dfrac{2 \times 2}{6 \times 2}} + {\dfrac{1 \times 1}{12 \times 1}} $ $ = - {\dfrac{4}{12}} + {\dfrac{1}{12}} $ $ = - \dfrac{{4} + {1}}{12} $ $ = -\dfrac{3}{12}$